Unspoken Rule
by Charlmeister
Summary: Shizuo and Izaya will never get along. But sometimes a spark goes off between them and they can't resist indulgence. There's a line that mustn't be crossed. Or else they may learn to love each other. Rated M for sexual content and language. One-shot.


_**Unspoken Rule**_

 ** _A/N: Hello all. It's been so long since I last published anything on this site. I fell out of love with writing fanfiction because it sort of hampered my ability to independently world build for my original stories. However, I've been roleplaying with a friend for awhile now and this story was inspired by our writing. A bit shameful that I'm breaking my dry spell with smut but nevertheless lol. Hope you enjoy._**

There were days Izaya and Shizuo could bear tolerating each other. Days when both were overwhelmed by an undeniable need. An intense and maddening desire that disrupted their functionality and corrupted their minds to see each other beyond mutual hatred. A need that – both begrudgingly admitted to themselves – couldn't be satisfied by anyone else.

For Izaya, Shiki wasn't attentive enough; his clumsiness belied any sexual experience for a man his age. For Shizuo, no one else but the crimson-eyed flea could handle his unrestrained passion. And the desire overtook them at random: in the middle of a fight when both faced each other bruised and bleeding; when they passed each other through Raijin corridors and their gazes drifted to each other. Neither could stop it. Both always succumbed and hated themselves for their weakness. Like now.

Shizuo had Izaya pressed to the lab door. Latch in place, door rattling on almost every impetus from the blond's thrusts. Izaya's palms were splayed against the smooth wood surface, but they balled into fists on one particularly forceful thrust. His nails scratched the wood, his Adam's apple bobbed on a nervous attempt to swallow a moan.

The damn beast was always too rough at school, the raven head thought. He looked down. His leaking cock jumped with each slap of hips against his ass. Both their pants pooled at their ankles. Izaya cupped the head of his penis to prevent drips of precome staining his pants.

Shizuo fucked into him deeper, pushing a raw moan from the other's lips.

"Shi-" Izaya reached behind him and grabbed at the other's hip. Without missing a beat, Shizuo shoved the lithe body into the door. Izaya's cheek pressed to the strip of cool glass in the door, breath fogging its surface with each labored pant.

"Don't…rough. Too rough." Shizuo's hard and deep thrusts against his prostate turned his mind to mush, robbing his ability to string together coherent thoughts.

"Shut up," Shizuo growled, fingers dug deep into the other's hips, marking pale flesh.

Though the air conditioning ran in the lab, both were sweaty from the friction – heat produced from their frantic and intense want for the other when they rushed into the lab room.

Izaya had gotten Shizuo's blazer off, but the blond had quickly discarded Izaya's black jacket and red shirt – both in a neglected heap a few feet from them. Behind him, Shizuo groaned something profane and Izaya's cock throbbed from heightened arousal. The deep, animalistic growls from the protozoan stirred something indescribable in him. Every time.

His nails bit into Shizuo's skin, broke the flesh, drawing a hiss from the blond. Izaya's lashes fluttered shut. He wanted more of those sounds. More of Shizu-chan wanting him. Badly enough to break him. His hipbones screamed from the iron grip of the other's fingers, but the pained mixed deliciously with the pleasure. It made his eyes water, caused his mouth to hang open and release moans and sobs and whimpers for more. For Shizuo to go deeper inside him.

Shizuo leaned forward into Izaya as his balls tightened. His face burrowed into the warm crook of Izaya's neck. Izaya's contractions around him shallowed his breathing. He was so close. He wanted it to end but didn't. The flea's flushed face did things to him – the deep rosy blush that went across his nose and cheeks, reaching to even the tips of his ears. It was an ugly expression, but he found he didn't dislike it. And those parted lips…

Izaya bit into the bed of his bottom lip and squeezed his eyes shut. He pushed back forcefully into Shizuo, butt grinding into the other's pelvis as his body seized up in orgasm.

Shizuo watched Izaya's facial muscles tense then relax into a blissed-out expression. His dilated gaze lifted to smoky ambers and the smug curl of his moist lips made Shizuo's hips buck involuntarily.

Izaya shoved at him then but was too late to stop the warm release of semen inside him. Lucky he wasn't a girl. But the prospect of cleaning up made him click his tongue rudely.

"How many times do I have to tell you not to come inside me?" The raven head cursed, eyes becoming hateful slits as he pushed Shizuo away from him.

"What was I supposed to do?" he grumbled heatedly, "let it out on the floor?"

Izaya pulled up his pants and shuddered at the wet feeling between his cheeks. "We're not the only ones who mess around at school," he said matter-of-factly. "You better have condoms next time."

Shizuo scoffed at the warning, hands busy buttoning his pants then buckling his belt.

"Who says there's gonna be a next time."

Izaya looked Shizuo up and down slowly, seeing through the flimsy bravado then tsked at him.

"You're bad at a lot of things, Shizu-chan. Lying's one of them. You know you're looking forward to the next time."

Shizuo's gaze narrowed dangerously, "I'm not."

"You know as much as I do that you love going balls deep inside me, marking me up as if I'm yours. Too bad you're not the only-"

Shizuo's hand grabbed around Izaya's neck and slammed him up into the door. Hard enough his spine hurt on contact with the wood. He grinned. Shizuo was too easy. Anger and evident jealousy swirled dark and intense in his eyes, sharpening the amber irises.

"I'll rip your fucking throat out."

Izaya cocked his head to the side, "Oooh, strong words Shizu-chan." He managed to speak around the grip threatening to crush his windpipe.

Shizuo released him after a few seconds and pushed him aside to open the door then storm out with a stiff glower on his face.

Release always brought him back to his senses. Why his body betrayed him almost every single time he came into contact with Izaya upset everything inside him. Because he couldn't explain it. He couldn't trace when it had become okay for them to express their hatred in such an intimate way. He wanted to get rid of how conflicted it made him feel. It fucked with his head. Made him think of doing unimaginable shit to the flea. Like kissing him. He shuddered and shook his head. They always had sex, but neither tried kissing the other. There were moments it seemed it would happen – both sometimes caught the other at times, gazing at each other's lips with a sort of distant wonder. But there was a tacit understanding between them. Kissing was a boundary they could never cross. Or else the nature of their sexual relationship would change.

Shizuo didn't want that happening. And he was sure the flea didn't either.

O.o.O.o


End file.
